Any combination that doesn’t have the adjectives in the correct order ends up looking weird.

It’s a fantastic big new red American house.

It’s a fantastic American big new red house.

It’s a big new American red fantastic house.

It’s a red fantastic American big new house.

It’s an American new red big fantastic house.

Not all languages use an order for adjectives. For example, in Polish it doesn’t matter what order the adjectives are in: “What a wonderful small blue bag!” and “What a blue small wonderful bag!” would sound just as “correct” as each other.

or Why do screens and monitors use red, green and blue pixels whereas printers use cyan, magenta and yellow ink?

The human eye contains three types of cones, light-sensitive cells that are sensitive to specific wavelengths (rather than rods, which are sensitive only to brightness/darkness).

The sensitivity of the three types of cones peak at wavelengths of 564-580 nanometres, 534-545 nm and 420-440 nm. These correspond to red, green and blue light, and by comparing the signals from the three types of cones the brain creates colours along red-green and blue-yellow axes (hence why there is no such colour as “greenish-red” or “yellowish-blue”). White light is created by the brain when all three cones are stimulated by the same amount.

For a colour to be perceived light must enter the eye. The big difference between the pixels on a computer screen and the inks used in printing is that light from screens enters the eye directly whereas light from printed materials must be reflected first. Screens use additive colour mixing, and printing inks use subtractive colour mixing.

To create the test image shown above on a screen, which emits light, the image is split into red, green and blue components. The darker areas are where less light is emitted.

To create this image in print, the image is split into cyan, magenta, yellow and black components (because the mix of cyan, magenta and yellow alone does not produce a perfect “strong” black, and would require the images to be lined-up perfectly). The lighter areas are where less ink is printed.

If both red and green light enter the eye in equal amounts, the brain creates the colour yellow.* To create the colour yellow on the printed page, both red and green light must be reflected from the page, and the only way to do this is to absorb blue. If yellow text is viewed under a blue light it will appear black, as all the light incident on the ink will be absorbed.

Colour

Additive (Light)

Subtractive (Inks)

Red

Emit red

Absorb green and blue

Green

Emit green

Absorb red and blue

Blue

Emit blue

Absorb red and green

Cyan

Emit green and blue

Absorb red

Magenta

Emit red and blue

Absorb green

Yellow

Emit red and green

Absorb blue

If cyan and magenta inks are printed on top of each other and illuminated by white light, the cyan will absorb red and the magenta will absorb green. The net effect of this is that only blue light is reflected, so printing cyan and magenta on top of each other creates the perceived colour blue.

If you tried to do this with, for example, red and green ink, the result would be black, as the red would absorb the blue and green and the green would absorb the red and blue. The reason you cannot print using red, green and blue inks is that red, green and blue ink absorbs more than one colour, whereas cyan, magenta and yellow do not. The only way to produce light colours is to start with light inks.

Ink

Absorbed

Reflected

Colour Perceived

Cyan

Red

Green and blue

Cyan

Magenta

Green

Red and blue

Magenta

Yellow

Blue

Green and red

Yellow

Cyan + Magenta

Cyan absorbs red

Blue

Blue

Magenta absorbs green

Magenta + Yellow

Magenta absorbs green

Red

Red

Yellow absorbs blue

Cyan + Yellow

Cyan absorbs red

Green

Green

Yellow absorbs blue

If you’d like proof of the table above, try printing out squares of red, green and blue and looking at them under a microscope.

It is easy to see, in the image of blue ink above, the cyan and magenta “pixels” (drops of ink) that create the blue colour. It’s more difficult, but possible, in the image of red ink below to see the magenta and yellow “pixels”.

* There is no way to guarantee that both you and I perceive the colour that we call yellow in the same way. We might both call it yellow, but we could be seeing vastly different things.

“GPS” is actually a brand name, and like “hoover” or “kleenex” has become a proprietary eponym, used to refer to a category of products despite just being one product in that category. There are other satellite navigation systems that offer the capabilities of GPS.

Operational

GLONASS

GLONASS (Globalnaya Navigatsionnaya Sputnikovaya Sistema) is the most developed of the GPS alternatives, and is operated by Russia. GLONASS uses twenty-nine satellites compared with the thirty-two satellites that make up the GPS constellation, and the GLONASS satellites are in a slightly lower orbit. Due to the orbital position of the satellites, GLONASS is slightly less accurate overall than GPS, but more accurate at high latitudes (both north and south) in locations such as Russia, because it is inclined at an angle of 65° to Earth’s equator as opposed to GPS’s 55°.

Many mobile phones already use a combination of GPS and GLONASS, and the availability of more satellites means that it is easier to get a line-of-sight satellite lock than when using GPS alone.

DORIS

DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) is a French system that operates the other way around to other satellite navigation systems: each DORIS satellite receives signals from between fifty and sixty ground stations, rather than it being the satellites that are broadcasting the signals. There are no dedicated DORIS satellites, but DORIS receivers are fitted to a number of satellites such as TOPEX/Poseidon and Jason.

The accuracy of DORIS is lower than GPS as ground positioning is not its primary purpose; it is designed to measure the position the orbits of the satellites aboard which DORIS receivers are fitted and to measure the height of the oceans.

BeiDou/COMPASS

BeiDou was a test system developed by China that used four satellites and covered China, India, parts of Japan and other countries.

The BeiDou system is being replaced to create BedDou-2 or COMPASS, and now uses sixteen satellites which cover the Asia-Pacific region, including Australia. By 2020 COMPASS should be able to offer global coverage, using thirty-five satellites, including five in geostationary orbit.

Development

Galileo

Galileo is a European satellite navigation system run by the EU and the European Space Agency; it plans to offer one-metre accuracy (compared with GPS’s fifteen-metre accuracy) and a search-and-rescue function for free, and will use a constellation of thirty satellites. Higher-precision (centimetre-resolution) data will be available to paying users. Five Galileo satellites have been successfully launched and placed, but the Soyuz rocket and Fregat “space-tug” used for the sixth satellite did not place it into the correct orbit.

Because Galileo satellites are placed in a higher orbit (23 200 km) than GPS satellites (20 200 km), there is a higher chance of being able to achieve a line-of-sight satellite lock, particularly in the “urban canyon” environment of modern high-rise cities. Galileo will also offer better coverage at high latitudes (e.g. northern Norway), where GPS coverage varies during the day due to the orbits of the GPS satellites.

It is highly likely that modern devices will use a combination of GPS, GLONASS and Galileo when the Galileo system becomes fully operational.

IRNSS

IRNSS (Indian Regional Navigation Satellite System) is an Indian satellite navigation system, the development of which is at least partially due to a desire to avoid reliance on foreign navigation systems. (During the India-Pakistan Kargil War in 1999, the US denied India access to GPS data.)

The system will consist of seven satellites in geostationary orbits, and will offer accuracy of below twenty metres within a radius of 3000 km of the centre of India, increasing to below ten metres over mainland India.

QZSS

QZSS (Quasi-Zenith Satellite System) is a Japanese system that is not a navigation system of its own, but rather augments the GPS system (it send signals compatible with standard GPS receivers). It will offer better coverage than GPS within Japan’s “urban canyons”, as the orbits of the four QZSS satellites will ensure that one satellite is always directly overhead of Japan. QZSS is specifically targeted at mobile applications, and will offer data transfer capabilities alongside positioning information.

Vienna Standard Mean Ocean Water (VSMOW) is the standard water used for calibrating instruments such as thermometers. Water will freeze and boil at different temperatures depending on the mix of isotopes it contains, and VSMOW standardises these ratios so that all experiments achieve the same results. (If you want to buy some VSMOW, it’ll cost you €180 for twenty millilitres, about twenty times more expensive than inkjet printer ink.)

Hydrogen

The hydrogen in water is one of three isotopes: hydrogen-1 (one proton), hydrogen-2 (one proton, one neutron, also known as deuterium) and hydrogen-3 (one proton, two neutrons, also known as tritium). Hydrogen-1 and deuterium are stable, but tritium is radioactive but has a long half-life (12.32 years). VSMOW contains one deuterium atom for every 6420 atoms of hydrogen-1, and one tritium atom for every 54.05 billion atoms of hydrogen-1. (The amount of tritium in VSMOW is so small that it is ignored for all but the most precise work.)

I tried really hard to come up diagrams to represent these ratios, but the amount of tritium is so small in comparison to the amount of hydrogen-1 and deuterium that it just disappeared every time.

Oxygen

The oxygen in water is also one of three isotopes, all of which are radioactively stable: oxygen-16 (eight protons, eight neutrons), oxygen-17 (eight protons, nine neutrons) and oxygen-18 (eight protons, ten neutrons). VSMOW contains one oxygen-17 atom for every 2632 atoms of oxygen-16, and one atom of oxygen-18 for every 498.7 atoms of oxygen-16.

My attempt at a diagram for the oxygen ratios was a bit more successful. If you enlarge the thumbnail below the blue square shows the amount of oxygen-18, and if you look really closely you can see a single green pixel in the bottom left-hand corner that represents oxygen-17.

Petrol expands as it gets warmer, and it expands a lot: 950 parts per million per kelvin rise in temperature. This may not seem like a lot, but you might be surprised.

Energy is released when petrol is burnt because the energy required to break the bonds between the carbon and hydrogen atoms in the petrol is less than the energy released when new bonds are formed between the carbon and hydrogen and the oxygen atoms from the air. See, for example, the combustion of octane (one of the main components of petrol) shown below.

*

This means that the amount of energy released by burning petrol depends on the number of atoms in the petrol, and therefore on the petrol’s mass, but you pay for petrol by the litre. You use mass but pay for volume.

Imagine buying petrol on a day when there is a fifteen degree Celsius difference in temperature between morning and afternoon; the petrol will expand by 14250 parts per million. One litre of petrol bought in the morning will expand to 1.014 litres in the afternoon. This means that the same amount of energy will cost you 1.43% more if you buy it in the afternoon rather than in the morning.

This is all a bit of a moot point, as petrol is stored in large underground tanks, and the temperature underground is a lot more stable than the temperature above ground. Perhaps you’d be better stockpiling petrol in the winter when ground temperatures are lower.